Titanium base alloys



United States Patent TITANIUM BASE ALLOYS No Drawing. Applicationlanuary23, 1957 Serial No. 635,593

Claims. (Cl. 75-1755) This invention pertains to titanium base alloyscon- 2,880,088 V Patented Mar. 31, 1959 "ice have at room temperatureeither a mixed alpha-beta or an all-beta microstructure depending on theheat treatment. As quenched from above the beta transus,they will havein general a substantially all-beta mierostructure; whereas as annealed"or after cold working, the structure will be mixed alpha-beta, when'the.total' beta promoter content is at the low end ofits range, i.e., frommore than to about while for total betapromoter contents above about20%, the alloys will have a substantially all-beta structure.

The following Table I gives the room temperature tensile properties ofrepresentative alloys according to the invention after fabrication at1600 F. to 40-mil sheet and V1 hour solution heat treatment at 1600 F.and

sisting essentially of about 0.5 to 9% and preferably 15 water quenched.

Table l Tensile Elongation, Average MBR, T Properties, Percent inp.s.1.X1,000 1 inch Percent Com osition, Percent VHN Reduc- (Ba aneeTitanium) (Surface) tion in 0.2% Ult. Area (Long.) ('Irans.) Otiset Str.Uniform Total Yield 187 0. 8 0. 8 48 71 21 51 2Ai-1sv 227 0 0 66 96 1824 32 2Al-24V..-. 251 0 0 92 102 9 12 20 0 5Al-30V 234 1. 0 1 0 102 10710 26 0.5Al-40V 255 0 0 107 111 10 83 6.75Al38.25 291 0 0 114 115 7 248.25Al-40J5V. 317 0. 4/1. 50 10 133 134 10 27 2Al-18Ta 254 0 0. 8 86 1047 ll 33 2Al24Ta.i- 247 0. 5 1. 0/7. 8 78 106 10 12 28 0 5Al-30Ta- 215 0.5 1. 0 71 74 15 31 2111-1601) 246 1. 0 1. 7 04 105 13 14 17 2Al-20C 2850.7 1.1 73 110 14 10 22 2Al-24Cb.. 247 0. 4 3. 0/6/2 73 110 14 16 220.5Al-Cb 222 0 0. 8 71 98 20 33 about 0.5 to 8% aluminum and from morethan 15% up to about 50% of one or more elements selected from the groupconsisting of vanadium, columbium and tan talum.

The alloys of the invention on solution treating and quenching fromabove the beta transus generally are characterized by a relatively lowyield strength and by excellent bend ductility and by high uniform andtotal tensile elongations, and hence are ideally adapted for forminginto sheet parts such as skins or wing and body coverings for airplanesand the like, where the ability to stretch uniformly is required. Anexception to this behavior are the alloys containing over about 25%vanadium, which do not possess the low yield strength and high uniformelongated characteristic of the other alloys by virtue of thesubstantial amounts of transformation to martensite they undergo duringcold working. However, the alloys with the higher vanadium contents haveexcellent strength and tensile and bend ductility and are eminentlysuitable for sheet forming operations, except where the ability tostretch uniformly is required. Thus these alloys in the form of rolledsheet and in the solution treated and quenched condition are easilyformed to shape. Thereafter they may be strengthened and hardened byaging at about 300 to 500 C.\ for about 1 to 16 hours.

As is known, pure titanium metal assumes at temperatures below about 885C. or 1625 F., a close-packed, hexagonal microstructure known as thealpha phase, while at this temperature and above, it assumes abodycentered cubic structure known as the beta phase.

Aluminum is a promoter or stabilizer of alpha titanium, while each ofvanadium, columbium and tantalum, is a promoter or stabilizer of betatitanium. Vanadium, columbium and tantalum are, moreover, betaisomorphous with titanium. Hence the alloys of the invention will Theabove alloys were prepared by are melting in a cold mold furnace in aninert or argon atmosphere. The titanium employed was of the commercialpurity type as produced by the magnesium reduction of titaniumtetrachloride according to the process of the Kroll US. Patent2,205,854.

It will be noted from the data of Table I that these alloys haveexcellent bend ductilities in both the longitudinal and transversedirections, on the order of 0 to 1 or 2T for most analyses. They alsopossess high tensile elongations both uniform and total, thus to permitof deep drawing and stretch forming operations. For these operations,bend ductilities up to about 20T and total tensile elongation valuesdown to about 9 or 10% are permissible.

These alloys, being generally of the beta type, will not tolerateexcessive additions of the interstitials carbon, oxygen and nitrogenwithout embrittlement, ordinarily not more than about 0.2% each or intotal amount.

This application is a continuation-in-part of application Serial No.398,868, filed December 17, 1953.

What is claimed is:

1. A titanium base alloy consisting essentially of about 0.5 to 9%aluminum, from more than 15% to about 50% of at least one beta promoterselected from the group consisting of vanadium, columbium and tantalum,balance substantially titanium, characterized in having a minimum bendductility of not over 20T and a minimum tensile elongation of about 10%.

2. A titanium base alloy consisting essentially of about 0.5 to 9%aluminum, from more than 15% to about 50% of at least one beta promoterselected from the group consisting of vanadium, columbium and tantalum,the aluminum content being on the low side of its range when the betapromoter content is on the high side .acteriized in having a minimumbend ductility ofnot over ZOT and a minimum tensile elongation of about10%.

5. A titanium base alloy consisting essentially of about 0.5 to 8%aluminum, from more than 15% to about 40% of tantalum, balancesubstantially titanium, characterized in having a minimum bend ductilityof not over 201 and a minimum tensile elongation of about 10%.

References Cited in the file of this patent UNITED STATES PATENTS2,754,204 Jafiee et al. July 10, 1956

1. A TITANIUM BASE ALLOY CONSISTING ESSENTIALLY OF ABOUT 0.5 TO 9%ALUMINUM, FROM MORE THAN 15% TO ABOUT 50% OF AT LEAST ONE BETA PROMOTERSELECTED FROM THE GROUP CONSISTING OF VANADIUM, COLUMBIUM AND TANTALUM,BALANCE SUBSTANIALLY TITANIUM, CHARACTERIZED IN HAVING A MINIMUM BENDDUCTILITY OF NOT OVER 20T AND A MINIMUM TENSILE ELONGATION OF ABOUT 10%